Cool autumn storm to bring rain across California and season’s first Sierra snow

Aerial view of a winding river in a snow-covered valley with mountains in the background
The Owens River courses through snow-covered Long Valley near Mammoth Lakes in February 2021.
(Brian van der Brug / Los Angeles Times)
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Rainfall and a significant drop in temperatures are expected around much of California this weekend as an early-season weather system moves across the state.

Over the next few days, forecasters are predicting cooling of up to 20 degrees and the first measurable snowfall of the season for the high Sierra.

“We’re looking at an area of low pressure that will be diving down the West Coast,” said David Sweet, a meteorologist with the National Weather Service office in Oxnard.


In Southern California, that will mean temperatures dropping 10 to 20 degrees below normal by Saturday morning and a very deep marine layer, he said. Along the coasts and in the valleys, highs Saturday are forecast to be in the mid- to upper 60s.

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Sept. 22, 2023

“Over the past couple of days, we’ve had temperatures in the 80s, some locations the lower 90s, but that’s going to change quite dramatically,” Sweet said.

Southern California will likely see some drizzling and light rain, with a slight chance for rainfall amounting to a few hundredths of an inch, but more significant precipitation is expected in Central and Northern California.

Rain could begin as early as Friday night in Northern California and western Nevada, forecasters said, with some areas seeing up to an inch of rain and the highest mountain peaks getting a few inches of snowfall.

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Sept. 28, 2023

Snow accumulation will likely remain above 8,000 feet of elevation, with the Tioga Pass in Yosemite forecast to get 2 to 3 inches, according to the National Weather Service, and the highest parts of the Sierra Nevada in Alpine and Mono counties getting anywhere from 2 to 9 inches.

Most of the precipitation will fall Saturday, with up to a quarter-inch of rain expected across the Central Valley, said Brian Ochs, a meteorologist with the National Weather Service in Hanford. The system will bring a chance of thunderstorms, which could include brief downpours, gusty winds and maybe even some small hail.


Much of the storm should push out of California by Sunday, with a warming trend returning by next week, Sweet said.